See also: Cross-piece (homonymy)

A crosses is an basic element of the Railway. It is a part posed across the way, under the Rail S, to maintain the spacing and the slope, and to transmit of it to the ballast the loads of the Véhicule S circulating on the rails. One uses mainly cross-pieces in Bois or Béton.

The travelage , i.e. the number of cross-piece to the kilometer is variable, generally of 1666 traverses/km to the SNCF.

Cross-pieces out of wooden

Traditionally the cross-pieces are out of hard wood, generally in Chêne or more rarely in Hêtre, material appreciated for its resistance and its flexibility, for its facilility of implementation, but of reduced lifespan (20 to 30 years) because it is putrescible. To prolong their lifespan, the cross-pieces out of wooden are in general impregnated under pressure of a pesticide, insecticide and fungicide, the Créosote. The cross-pieces out of wooden still represent the very great majority of the cross-pieces used in the world. To avoid the appearance of slits, related to the successions of wet and dry periods, one can ring the heads of cross-pieces using metal strip iron, it is the hooping .

Their dimensions are generally, with the SNCF, of 2,6 m length, 25 cm broad and 15 cm thickness. It are notched to allow the support of the rails. the zone of support or table of sabotage is delimited so as to determine the spacing of the rails and their slope (at the 1/20 with the SNCF).

The fixing of the rails on the cross-pieces out of wooden is done thanks to coach screws and elastic fasteners, sometimes provided with rubber soles to limit the noise.

The recycling of the cross-pieces out of wooden is regulated in several countries because of the harmfulness of the creosote, carcinogenic classified product.

Concrete cross-pieces

The concrete cross-pieces have one more important lifespan (50 years). There exists about it of two types:

• Bibloc, made of two concrete blocks connected by a metal spacer, which absorbs the efforts in medium of cross-piece
cast solid
• out of prestressed concrete, thinned in their central part, high-strength wire armies.

The use of the concrete cross-pieces is in clear increase, as well because of their intrinsic quality as for the high price of the cross-pieces out of wooden. The concrete cross-pieces, by their important weight, ensure a good anchoring of the way in the ballast. They are used in particular for the new lines at high speed. The fixing of the rails is done by elastic fasteners provided with insulating rubber devices.

Metal cross-pieces

The metal cross-pieces, in Steel, are hardly any more used. They are noisy, especially at raised speed, are anchored less better in the ballast because of their lightness, and not being insulating are not easily compatible with the systems of indication calling upon the currents of way (the character isolating from the fasteners must be particularly neat). They also make very difficult the maintenance of the geometry of the way by Bourrage. Indeed, their form does not make it possible the Bourreuse S to insert ballast under the cross-piece.

See too

• Railroad
• Railway

cross

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